The DIBOSA Study: The 6MWT Helps Predict PH in Patients with SSc

by Phyllis Hanlon, Contributing Writer

Research has found that World Health Organization (WHO) Group 1 pulmonary hypertension (PH) (pulmonary arterial hypertension, or PAH) affects 8 to 12 percent of patients who have systemic sclerosis (SSc, a form of scleroderma – a disease that causes hardening and tightening of the skin and connective tissues) and can be a primary cause of declining health and death in people with SSc. In addition, people with SSc are at risk for other types of PH (non-PAH) because of the effect SSc may have on the lungs and heart. Finding easy, effective ways to diagnose the type of PH in people with SSc as early as possible can help clinicians develop appropriate treatment plans and may improve patient outcomes.

Abhishek Gadre, M.D. and Kristin B. Highland, M.D. of the Cleveland Clinic, Cleveland, led a team of researchers in the development of a new risk-scoring system, the DIBOSA score, to determine the risk of developing PH and disease outcomes in patients with SSc. DIBOSA obtains its measurements from the six-minute walk test (6MWT), an established tool that often is used to evaluate patients with lung and heart diseases. Their findings were published in October 2017.

The research team assembled already collected data from 286 SSc patients who had undergone a 6MWT at Cleveland Clinic between 2003 and 2013. Nearly half of the SSc patients also had PH. When the researchers considered at least 25 different variables, including eight demographic variables (e.g., age, race and gender) and 16 6MWT variables (e.g., heart rate and need for supplemental oxygen), three were found to best predict risk and severity of PH and were included in the final score formula:

Variable Score Assignment
Six-minute walk distance (6MWD) <360m = 1
Borg dyspnea scale >2 Borg dyspnea = 1
Saturation of oxygen at the conclusion of the 6MWT <95% saturation = 1

The researchers found that the DIBOSA score is a successful predictor of disease severity and mortality in patients with SSc. The risk of patients with SSc developing PH increased as the DIBOSA score increased:

The researchers recommended that, based on these risks, patients with a score of 1 or 2 should undergo echocardiogram and pulmonary function testing (PFT). Patients with a score of 3 should be referred to a PH program to undergo right heart catheterization.

In conclusion, Dr. Highland said that the DIBOSA score system is potentially an easy and inexpensive way to identify SSc patients at low, intermediate and high risk for PH. Further research will be needed to see if this risk score works as well in another center (or group of centers), as this study was only completed at the Cleveland Clinic. As the researchers used previously collected data from SSc patients over a long period of time, further research will be needed to see if the DIBOSA score system works as well in identifying previously unknown PH in SSc patients. However, the DIBOSA score system potentially offers an important new tool to improve a clinician’s ability to identify SSc patients at risk for PH, especially in clinics with fewer resources who see low-income patients.

2018-10-05T20:46:46+00:00 October 5th, 2018|